The nature of underground mining operations makes them highly dangerous.
For example, in the case of a mine collapse, the supply of breathable air can be severely compromised, placing the miners in great danger.
Furthermore, mines are often highly susceptible to the infusion of noxious gases (e.g., methane, carbon monoxide, etc.). This situation can occur in many scenarios, even where there is no catastrophic mine collapse. Gas pockets can be exposed at any time and without notice, and can be life-threatening even where the mine is structurally intact. In any of these situations, once the gas enters the space occupied by the miners, their lives are in serious danger.
In all of these situations, the miners must quickly recognize the danger and then must obtain an supply of breathable air. This supply of breathable air may be provided by various means, e.g., a filtered system, a conventional “open-loop” self-contained breathing apparatus (SCBA), a conventional “closed-loop” self-contained breathing apparatus (SCBA), a solid state oxygen generator, etc. The equipment for providing the supply of breathable air is commonly referred to as a Self Rescuer and is generally carried by the miners on their belts. Once the miners have “switched over” to this supply of breathable air, they must then escape the danger zone. In the case of a “benign” gas pocket, escape may be as simple as walking or riding a mine car out of the affected area. In the case of a mine collapse, gas explosion, or other serious event, escape may involve crawling, tunneling, walking or just waiting for rescue. In any of these latter situations, there is a significant danger that the supply of breathable air may be depleted before the miner has reached a safe location.
At the same time, in many of these situations, it is not possible for the miners to use conventional negative pressure filtered respirators, powered air purifying respirator (PAPR), etc. due to the nature of the threat, e.g., the possible air contaminants (e.g., some gases), the physical state of the ambient air (e.g., super-heated air), etc. In these situations, a self-contained breathing apparatus (SCBA) is required.
Conventional “open-loop” SCBA units generally consist of a tank of compressed gas (usually ambient, but filtered, air) with the flow controlled by a regulator or demand valve. One of the major inefficiencies of these units is that the exhausted and/or exhaled air (still containing significant usable oxygen) is vented to the environment and thus lost to the user. Much greater efficiencies (translating into smaller, lighter units and longer supply times) can be attained by using “closed loop” SCBA units which recycle the exhaust air and recover the oxygen, and/or remove the undesirable products of respiration (mainly carbon dioxide). A device utilizing this approach is commonly referred as a “Rebreather”. See FIG. 1.
Any respirator device, whether filtered, open-loop SCBA, closed-loop SCBA, etc. has a limited capacity to supply breathable air. If the miners exhaust the capacity of the respirator device while still in a dangerous environment, the miners must be able to access a replacement breathing component and make the “change-over” to the replacement breathing component without “breaking the seal” or otherwise exposing themselves to breathing in the potentially noxious gases.
As a result, a primary object of the present invention is to provide a self-contained breathing apparatus (SCBA) which is able to safely and quickly connect to a replacement breathing component without “breaking the seal” so that the replacement breathing component can supply additional breathing capacity to the user. Preferably, the replacement breathing component can take any number of forms, e.g., the working portion of another “closed-loop” SCBA, an air bottle, a carbon monoxide filter respirator, etc.